Help with certbot for spice-web-client

I’m following the steps shown in the libvirtd guide but these steps confuses me:

services.networking.websockify = {
  enable = true;
  sslCert = "/https-cert.pem";
  sslKey = "/https-key.pem";
  portMap = {
    "5959" = 5900;
  };
};

How am i supposed to generated those certificates? Do i need to run cerbot? Someone please guide me in the right direction.

First of all, please use the official wiki at wiki.nixos.org.

Secondly, the wiki entry tells you where the certs are coming from

Also, I use letsencrypt dns mode to get https cert and key

link can generate the certs for you.